This invention relates to intraocular lenses (IOLs). More particularly, the invention relates to IOLs placed in the anterior chambers of eyes, and to methods for inserting IOLs in such anterior chambers, which reduce the risk of malshaping the iris of the eye, for example, ovalling the pupil formed by the iris.
Intraocular lenses (IOLs) are commonly used to modify or enhance vision. IOLs can be placed at various positions or locations within the eye. For example, IOLs can be placed in the anterior chamber of the eye, that is, the region of the eye posterior of the cornea and anterior of the iris.
Referring now to FIG. 1, an anterior IOL (AIOL) 10 of the prior art is shown implanted in an eye 12. The eye 12 comprises a cornea 14 shown to the left and an iris 16 shown in the middle of the eye. It is to be understood that the cornea 14 is at the front of the eye 12. The iris 16 divides the eye 12 into an anterior chamber 18 at the front of the eye and a posterior chamber 20 in back of the iris. The iris 16 also defines the pupil 22, which is an opening in the middle of the iris. In front of the iris 16 is the scleral spur 24. The scleral spur 24 and the iris 18 delimit the ciliary band 26. Behind the iris 16 is the ciliary process 28, from which extends the ciliary muscle 30. The ciliary muscle supports the natural crystalline lens 32 of the eye 12. The iris 16 and the ciliary process 28 define the sulcus 34.
FIG. 1 shows the AIOL 10 implanted in the anterior chamber 18 of the eye 12. The AIOL 10 is comprised of an optic 40 that is supported in front of the pupil 22 by fixation members 42, sometimes known as loops or haptics. The optic 40, for the AIOL 10 and other IOL""s described herein, may be considered as including an optical portion for focusing light at or near the retina (not shown) of the eye 12. The fixation members 42 extend from the optic 40 to rest in the ciliary band 26, and are designed to minimize compression stress on the optic 40 and inhibit forward vaulting of the optic. If the optic 40 vaults and contacts the cornea 14, an undesirable condition known as endothelium tough may occur. However, this condition may occur from the fixation members 42 merely residing in the ciliary band 26.
Current anterior chamber IOLs have fixation systems that are shorter in one dimension to facilitate passage through a minimum incision size. For example, one AIOL of the prior art includes a rectangular arrangement of footplate haptics. Such AIOLs have a tendency to malshape, e.g., oval, the iris of the eye, which is not acceptable from a cosmetic point of view. In addition, malshaping is an indication of a possible misfit of the IOL, which can result in impaired vision and/or additional surgery to replace the IOL.
It would be advantageous to provide anterior chamber IOLs which reduce the risk of malshaping the iris of the eye.
New IOLs for implantation in eyes, in particular in anterior chambers of the eyes, have been discovered. The present IOLs effectively reduce the risk of malshaping the iris of the eye, are adapted to be effectively fixated in the anterior chamber of the eye, and provide desired vision correction. In general, the present IOLs include fixation systems which facilitate effectively fixating the IOLs in the anterior chamber of the eye and, in addition, reduce or even substantially eliminate the risk of malshaping the iris. The present IOLs are straightforward in construction and can be produced using conventional and well known techniques. Thus, the present IOLs provide substantial benefits without dramatic changes in IOL design and insertion procedures.
In one broad aspect of the present invention, IOLs for implantation in an eye, in particular an anterior chamber of the eye, are provided. Such IOLs comprise optics and fixation systems. The optic has an optical axis and is effective to direct light toward the retina of the eye. The present IOLs can be employed with or without the natural lens being present. One advantage of having the present IOLs in the anterior chamber of the eye is that the optic of the present IOL is spaced apart from the natural lens, if present. Such separation advantageously protects the natural lens from cataract formation or other detrimental conditions which may be caused by contact between the optic and the natural lens.
The present fixation system is coupled to the optic and includes at least three distal ends extending radially outwardly of the optic. These distal ends are adapted to be in contact with a peripheral region of the anterior chamber of the eye, for example, to facilitate fixating the IOL in the anterior chamber. Each of the distal ends of the fixation system is substantially equidistantly spaced apart from the closest circumferentially adjacent distal ends. This structure is very effective in spreading or equalizing the stress on the peripheral region of the anterior chamber and the iris caused by the presence of the IOL. Such substantial stress uniformity is believed to be one important factor in reducing the risk of malshaping the iris as a result of the presence of the IOL in the anterior chamber. In one embodiment, the IOL of the present invention is made of a material that is resilient enough to be folded for insertion through narrow access passages or incisions into the anterior chamber of the eye.
In addition, the distal ends preferably include a structure enlarged relative to a portion of the fixation system proximal of the distal ends. Such enlarged structure at the distal end is advantageous, for example, in guarding against the harmful effects of excessive contact stresses between the fixation system and the tissue at the peripheral region of the anterior chamber, which is susceptible to being damaged. The present IOLs are effectively fixated in the anterior chamber of the eye and effectively reduce one or more of the detrimental effects often caused by having anterior chamber IOLs fixated in the anterior chamber.
The present IOLs can be produced in any suitable manner. A number of conventional IOL manufacturing techniques, which are well known in the art, are effective. Such techniques include, but are not limited to, polymerization techniques, and/or polymeric material molding, casting and/or machining. The fixation members can be provided, together with the optic, as part of a single piece lens, or can be coupled to the optic during formation of the optic, for example, during polymerization to produce the optic, or after the optic is formed. The specific methodology or methodologies by which the present IOLs are produced is not a critical aspect of the present invention.
Any and all features described herein and combinations of such features are included within the scope of the present invention provided that the features of any such combination are not mutually inconsistent.
These and other aspects and advantages of the present invention will become apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.